Fire and explosion detectors



July 19, 1955 w. KAGAN FIRE AND EXPLOSION DETECTORS Filed May 9, 1952 FIG.

INVENTOR. WILL/AM KA A TTOR/VEY United States Patent Ofifice 2,713,624 FIRE AND EXPLOSION DETECTORS William Kagan, University City, Mo. Application May 9, 1952, Serial No. 287,058 4 Claims. (Cl. 200138) This invention pertains to safety devices for shutting 01f electrically-operated service appliances such as furnaces, gas valves, air-conditioning systems, and the like in emergencies such as fires or explosions.

An object of this invention is to provide such a device which may be mounted adjacent a furnace or other appli- Which shall respond to excessively high temperature the region to be protected to make certain of the safety of restarting.

Generally stated, the device of the invention comprises which may be installed at such point as may be subject to excess temperature if an emergency, such as a fire or explosion, should occur. Said switch is spring biased for movement to its open-circuit position but is held in a thermostatic element exposed Said element is set to sion, may move said globule to open the circuit momentarily, thereby causing circuits.

A preferred embodiment of this invention is illustrated in the accompanying drawing, in which:

Figure 1 is a vertical central section of a protective device embodying this invention,

Figure 2 is a side view of Fig. 1, with parts in section,

Figure 3 is a section on line 33 of Fig. 1,

Figure 4 is a section on line 44 of Fig. 2,

Figure 5 is an enlarged section of the mercury switch, and

Figure 6 is a diagram of electrical connections showing one arrangement of circuits in accordance with this invention.

Referring to the drawing, ring which may be arranged outlet box or other support.

1 designates an attachment for mounting on a standard forms the second switch terminal.

A supporting bracket 10, of circular form has an annular groove 11 encircling a central hub 12. A bushing 13 passes through a perforation in the frame 3 and is thread 2,713,624 Patented July 19, 1955 with a laterally extending finger 31.

- relay is energized it holds the bracket 10 to the frame 3. If this the frame 3 and bearing against the bracket 10. A second bracket 15, similar in shape to the bracket 10, has an annular groove 16 matching the groove 11 when said two brackets are assembled facmg each other as shown in bushing 13 and provided with a manipuiating head 18. The bracket 15 is secured to the shaft 17 by a set screw 19.

The switch 5 is fixed to the end of the pivot shaft 17 by a screw 21.

the bracket 15 is formed with a depression 32 leaving a surrounding atmosphere.

In use this device may be connected in control circuits as shown in contact 42; thence via the bar 37, conductor 43, relay 36 and conductor 44 back to the transformer 35. The other sition by the finger 31 engaging the stop 33. While the the bar 37 in position to close conductors 39, 40 and 41 to the all the circuits to the service appliances as well as the contact 42 which controls the relay itself. The thermostat is set as described so that at a predetermined temperature it will turn the finger 31 so as to release the stop 33 and the bracket 15. As shown in Fig. 3, this movement of the finger 31 is in the same general direction as that of the stop 33 as urged by the spring 22, but in a path which deviates from that of the stop to effect the release; Thus no appreciable extra load, such as friction between these parts, is imposed on the bimetallic element 2.5 during this movement. When this happens, the switch opens and the relay 35 is Clo-energized, and the bar 37 drops, opening the circuits 48, 49 and 5t) and shutting down the appliances 45, 4-6 and 47. At the same time the relay circuit is opened at the contact 42.. Also, since the stop 33 has been moved past the finger 3'1, the switch 5 will remain open even if a drop in temperature should cause the thermostat to return to its normal condition. This provides opportunity for inspection of the premises before restarting the various appliances. An extra contact 51 may be arranged to be engaged by the bar. 37 when it drops, to close an independent circuit to a suitable alarm device 52. Such circuit may have its own source of. energy, represented by the battery 53 in Fig. 6.

In order to restore operation when the trouble has been cleared, the switch 5 is closed by manipulation of the head 18, at the same time re-engaging the finger 31 with the stop 33. Thereafter a switch 54, short-circuiting the contact 42, is closed to energize the relay 36 which thereupon lifts the bar 37 to close the other contacts and start the appliances 45, 46 and 47. The switch 54 should be a push button or other self-opening switch, so as to restore control of the relay to the contact 42. An emergency switch 55, short-circuiting the switch 5, is provided so that, in the event of trouble with the switch 5 or the thermostat, the appliances may be operated temporarily without them.

The arrangement of the switch 5 is such that it may be adjusted to afford protection against violent shocks due to explosions, tornadoes, or like causes. As shown in Pig. 5, the closed-circuit setting may be so adjusted, as by positioning the clip 20 with respect to the bracket 15, that the globule 7 makes just sufficient contact with the terminal 6 to carry the required current. Said globule, being freely mobile in the tube 8, will be displaced by a substantial shock, breaking contact with the terminal 6 and opening the energizing circuit of the relay 36. In order to avoid such action taking place as the, result of mere vibration of the supporting structure, however, the attachment ring 1 may be mounted with pads 56, of vibration-absorbing material such as rubber, felt or the like, interposed between it and the supporting structure in any suitable manner.

It will be seen that this invention provides a simple and effective device for protecting premises and installations against hazards engendered by the operation of service appliances, such as furnaces, gas supply lines, airconditioning systems and the like, in emergencies resulting from fires, explosions and other accidental occurrences. The device is responsive to high temperature and shock, one or both of which are usually present in such emergencies. Once shut down, the appliances are not restarted automatically upon return of conditions to normal, but must be restarted manually so that inspection may be made before resuming operation.

I claim:

1. In a device for the purpose set forth, an L-shaped supporting bracket having a vertical leg and a horizontal leg, a circular housing member resting against one face of said vertical leg and having a peripheral flange projecting away from the leg, said housing member having a centrally disposed internally threaded tubular boss, said vertical leg having an opening alined with said boss, a tubular bearing member extending through. said opening.

and screwed into said boss, said bearing member having a flanged head bearing against the other face of the vertical leg, at second housing member having a peripheral flange and a hollow boss engaging in alinement with the flange and boss of the first housing member and providing a circular channel between the flanges and bosses, a shaft extending through said bearing and the boss of the second member and having the latter fixed thereto, pins projecting into said channel from the housing members respectively, a coiled tension spring mounted in said channel and having its ends hooked on said pins and urging the second housing member to rotate on the first housing member, said housing members being angularly adjustable relatively to each other and to said supporting bracket, latch means engaging the second housing member to hold it releasably from rotation, and a mercury switch carried by said shaft.

2. in. a device for the purpose set forth, an L-shaped supporting bracket having a vertical leg and a horizontal leg, a circular housing member resting against one face of said vertical leg and having a peripheral flange projecting away from the leg, said housing member having a centrally disposed internally threaded tubular boss, said vertical leg having an. opening alined with said boss, a tubular bearing member extending through said opening and screwed into said boss, said bearing member having a flanged head bearing against the other face of the vertical leg, a second housing member having a peripheral flange and a hollow boss engaging in alinement with the flange and boss of the first housing member and providing a circular channel between the flanges and bosses, a shaft extending through said bearing and the boss of the second member and having the latter fixed thereto, pins projecting into said channel from the housing members respectively, a coiled tension spring mounted in said channel and having its ends hooked on said pins and urging the second housing member to rotate on the first housing member, latch means engaging the second housing member to hold it releasably from rotation, a mercury switch carried by said shaft, and thermostatic means effecting release of said latch means at a predetermined temperature.

3. In a safety switch of the character described, a support, a pair of similar housing brackets having matching circumferential grooves, said housing brackets being mounted face to face with each other so as to form together an annular housing, one of said brackets being adjustably fixed to said support, a shaft journalled on said support to pass coaxially through said fixed bracket, the other of said housing brackets being mounted on said shaft for rotation relatively to said fixed bracket, a coil spring. housed in said annular housing and attached at each end to a different one of said brackets, a mercury switch mounted on said rotatable brac 'et, a stop on said last bracket, a latch engageable with said stop and mounted on said support for rotary movement on an axis transverse to that of. said shaft to disengage said stop, and a thermostatic element connected to rotate said latch in accordance with. changes of temperature.

4. In a safety switch of the character described, a support, a pair of similar housing brackets having matching circumferential grooves, said housing brackets being mounted face to face with each other so as to form together an annular housing, one of said brackets being adjustably fixed. to said support, a shaft journalled on said support to pass coaxially through said fixed bracket, the other of said housing brackets being mounted on said shaft for rotation relatively to said fixed bracket, a coil spring housed in said annular housing and attached at each end to a different one of said brackets, a mercury switch mounted on said rotatable bracket, a stop on said last bracket, a latch engageable with said stop, and a thermostatic element connected to said latch and opthe same in direction as the movement of said stop crating. under, rise oftemperature to move the same general.

5 by the action of said spring but in a path de'viaiing from 1,637,042 that of said step so as to release the latter. 1,656,706 1,761,772 References Cited in the file of this patent 1354349 UNITED STATES PATENTS 5 2,567,112

Brobst Mar. 24-, 1925 Hutt July 26, Hann Ian. 17, Carpenter et a1. June 3, Liber Apr. 12, Kagan Sept. 4, Kagan Feb. 12, 

